I've been keeping a simple text-file journal since 2010: one file per day, simple file naming conventions and directory structure (~/Journal/2017/2017-01-26.txt

I've been keeping a simple text-file journal since 2010: one file per day, simple file naming conventions and directory structure (~/Journal/2017/2017-01-26.txt and such). I use it to track food intolerances and health issues mostly, though also record the names of books as I finish reading them, movies I see, and significant life events. I've got a handful of scripts to help me do things like grep through ranges of dates, and search for items with simple tags so I can, for instance, easily find when I last ate a particular food. It is simple and works for me, so I have never invested the time or effort to make something more structured, though I might write a few more tools to help with the structure I do have,at some point.